INFUSORIA — ENCYSTING PROCESS. 



419 



272. Tlie recent observations of Stein and other Microseopists 

 have dravs^n attention to another very curious mode of propaga- 

 tion, the phenomena of which were completely misapprehended 

 by Prof Ehrenberg. Many Infusoria at certain times undergo 

 an encysting process ; that is, their body secretes from its surface 

 a sort of gelatinous case, which hardens so as completely to 

 enclose it, the Animalcule, however, still remaining free in the 

 interior of its coffin-like investment. Previously to the forma- 

 tion of this cyst, the Animalcule loses its activity, its form 

 becomes more rounded, and its cilia or other filamentous pro- 

 longations are lost or re- 

 tracted, as is well seen in Fio. 198. 

 Vortieella (Fig. 198, a); 

 and it was not, perhaps, 

 very unnatural, that the 

 encysting process should 

 have been considered by 

 Prof. Ehrenberg as the 

 expiring effort of life. If 

 the cysts and their con- 

 tents, however, be atten- 

 tively watched, it will be 

 seen that the process is 

 preliminary to a produc- 

 tion of new individuals ; 

 and this may take place 

 in different modes. For 

 sometimes the substance 

 of the body appears to 

 break up (c, d) into nume- 

 rous "gemmules," which 

 are analogous to the 

 " zoospores" of Proto- 

 phytes, and which, like 

 them, are set free by the 

 bursting of the parent 

 cell(E), swimming forth to 



dpvplonp thPTnqplvPS intn —*> full-grown individual in its 



Ueveiope tnemseives miO ^^^^ _,.^^,^j of cilia; 6, nucleus i c, comraclile vesicle ;-B, 



new individuals or the a cyst separated from its slalk; — c, the same more advanced, 



same kind though at first *^® nucleus broken up imo spore-like globules; — D, the same 



■I "U * more developed, the original liody of the Vortieella, d, havings 



pernapS Oearmg no re- become sacculated, and containing many ctear spaces; — e, 



semblance to the type of *^"^ of the sacculations having burst through the enveloping 



tliAir T%rPflofPHar>r Tn "y^'' " S^''"'"''"" ■"''ss. «■ containing the spores, is dis- 



lueil _ pieuectJBBOI. XU charged;— p, transformation of encysted Vortieella (b) into 



other instances, however, form of Adneta,- b, nucleus;— s, stalked Aclneta form of 



Onlv a sinffle Offsnrine' is Vonicella, enclosing a young one, the result of the transfor- 



- ^ -. -&- --t^ ^ mation of the nucleus;— H, young free Vortieella; a, 6, c, as 



developed iromthe "nU- i„ Fig. l;^, posterior circlet of cllla. 



cleus" of the original cell- 

 body, which offspring may have an entirely dissimilar form ; and 

 this latter change occurs in Vortieella, in conjunction with other 



Development and Metamorphosis of Vortieella microstimia : 

 encysted state; a, retracted 



